Remains were found in the Tiffanian (Middle Paleocene)-age strata of Princeton Quarry in Wyoming (United States).

The holotype is in the collection of the Peabody Museum of Natural History at Yale University.

Remains were found in the Puercan (Lower Paleocene)-age strata of the San Juan Basin of New Mexico (United States).

Remains were found in the Middle-Upper Paleocene-age strata of the Tongue River Formation in North Dakota (United States).

Remains were found in the Torrejonian-Tiffanian (Middle Paleocene)-age strata in the Gidley Quarry of Montana and in Wyoming, North Dakota and Alberta, Canada.